1. Field of the Invention
The present invention relates to an anti-viral compound, in particular to a cyclohexenone compound isolated and purified from Antrodia camphorata extracts and can be applied in inhibition of hepatitis B virus.
2. The Prior Arts
The Hepatitis B Virus (HBV) is a small double-stranded, enveloped virus of the Hepadnviridae family, which causes sustained noncytopathic liver infection. It is the only DNA virus among all human liver viruses. The membrane of hepatitis B virus composed of 25% lipid and 75% glycoprotein. The major component for glycoprotein is hepatitis B surface antigen (HbsAg). Core region of HBV particle contains hepatitis B envelop antigen (HbeAg). HBeAg is a secretory protein which can pass through human placenta from mother to fetus in early stage, and elicits cytotoxic T-cells tolerance to HbeAg due to immature immune systems in babies. The immune system in human can not clear HBV and causes high-level HBV replication. HBeAg is also considered as a tolergen. Therefore, the levels of HBsAg and HBeAg can be used as markers of hepatitis for evaluating the HBV replication and secretion. The World Health Organization indicated that about two billion people show evidence of past or current infection with HBV, which has a high prevalence and incidence rate. Vertical transmission is the main path of HBV infection. The virus can cause acute hepatitis, chronic hepatitis, and liver cirrhosis, even developed to liver cancer. Around 90% of the males above 30 years old in Taiwan were infected with HBV. 15% to 20% of them become life-long carriers, and may die from sequelae including liver cirrhosis and liver cancer. Therefore Taiwan is a hyperendemic area for HBV infection and liver cancer.
The HBV infection is closed related to liver diseases and liver cancer as mentioned above. Anti-viral therapy through interference and inhibition of viral replication, and elimination of chronic infection is the major purpose for the related studies. Treatments with interferon, anti-viral drugs or vaccines show beneficial effects recently. However, chronic carriers of hepatitis B can not be cured completely; this is the main reason for HBV related liver diseases and high mortality. Therefore, development of HBV inhibiting anti-viral drugs is crucial at present.
Antrodia camphorata is also called Chang-Zhi, Niu Chang-Zhi, red camphor mushroom and the like, which is a perennial mushroom belonging to the order Aphyllophorales, the family Polyporaceae. It is an endemic species in Taiwan growing on the inner rotten heart wood wall of Cinnamomum kanehirae Hay. Cinnamoum kanehirai Hay is rarely distributed and being overcut unlawfully, which makes Antrodia camphorata growing inside the tree in the wild became even rare. The price of Antrodia camphorata is very expensive due to the extremely slow growth rate of natural Antrodia camphorata that only grows between Junes to October.
The fruiting bodies of Antrodia camphorata are perennial, sessile, hard and woody, which exhales strong smell of sassafras (camphor aroma). The appearances are various with plate-like, bell-like, hoof-like, or tower-like shapes. They are reddish in color and flat when young, attached to the surface of wood. Then the brims of the front end become little curled tilted and extend to the surroundings. The color turns to be faded red-brown or cream yellow brown, with ostioles all over. This region is of very high medical value.
In traditional Taiwanese medicine, Antrodia camphorata is commonly used as an antidotal, liver protective, anti-cancer drug. Antrodia camphorata, like general edible and medicinal mushrooms, is rich in numerous nutrients including polysaccharides (such as β-glucosan), triterpenoids, superoxide dismutase (SOD), adenosine, proteins (immunoglobulins), vitamins (such as vitamin B, nicotinic acid), trace elements (such as calcium, phosphorus and germanium and so on), nucleic acid, agglutinin, amino acids, steroids, lignins and stabilizers for blood pressure (such as antodia acid) and the like. These physiologically active ingredients are believed to exhibit effects such as: anti-tumor activities, increasing immuno-modulating activities, anti-allergy, anti-bacteria, anti-high blood pressure, decreasing blood sugar, decreasing cholesterol and the like.
Triterpenoids are the most studied component among the numerous compositions of Antrodia camphorata. Triterpenoids are the summary terms for natural compounds, which contain 30 carbon atoms with the pent acyclic or hex acyclic structures. The bitter taste of Antrodia camphorata is from the component of triterpenoids. Three novel ergostane-type triterpenoids (antcin A, antcin B, antcin C) were isolated by Cherng et al. from the fruiting bodies of Antrodia camphorata (Cherng, I. II., and Chiang, II. C. 1995. Three new triterpenoids from Antrodia cinnamomea. J. Nat. Prod. 58:365-371). Three new compounds zhankuic acid A, zhankuic acid B and zhankuic acid were extracted from the fruiting bodies of Antrodia camphorata with ethanol by Chen et al. (Chen, C. H., and Yang, S. W. 1995. New steroid acids from Antrodia cinnamomea,—a fungus parasitic on Cinnamomum micranthum, J. Nat. Prod. 58:1655-1661). In addition, Cherng et al. also found three other new triterpenoids from the fruiting bodies of Antrodia camphorata, which are sesquiterpene lactone and 2 biphenyl derived compounds, 4,7-dimethoxy-5-methy-1,3-benzodioxole and 2,2′,5,5′-teramethoxy-3,4,3′,4′-bi-methylenedioxy-6,6′-dimethylbiphenyl (Chiang, H. C., Wu, D. P., Cherng, I. W., and Ueng, C. H. 1995. A sesquiterpene lactone, phenyl and biphenyl compounds from Antrodia cinnamomea. Phytochemistry, 39:613-616). In 1996, four novel ergostane-type triterpenoids (antcins E and F and methyl antcinates G and H) were isolated by Cherng et al. with the same analytic methods (Cherng, I. H., Wu, D. P., and Chiang, H. C. 1996. Triteroenoids from Antrodia cinnamomea. Phytochemistry. 41:263-267). And two ergostane related steroids, zhankuic acids D and E together with three lanosta related triterpenes, 15 alpha-acetyl-dehydrosulphurenic acid, dehydroburicoic acid, dehydrosulphurenic acid were isolated by Yang et al. (Yang, S. W., Shen, Y. C., and Chen, C. H. 1996. Steroids and triterpenoids of Antrodia cinnamomea—a fungus parasitic on Cinnamomum micranthum. Phytochemistry. 41:1389-1392).
Although Antrodia camphorata extracts were reported to have the abovementioned effects from the previous experiments, and the components were analyzed in succession, further experiments are needed to identify the effective composition to inhibit HBV infection and to treat the HBV-related liver diseases. The natural components of Antrodia camphorata extracts will greatly contributes great beneficial effects in treating HBV-related liver diseases include acute hepatitis, chronic hepatitis, liver cirrhosis, and liver cancer if the real effective composition is found.